Insoluble anode loop in copper electrodeposition cell for interconnect formation

ABSTRACT

Embodiments of the invention generally provide a method and apparatus for plating a metal on a substrate. The electrochemical plating system generally includes a plating cell having an anolyte compartment and a catholyte compartment, the anolyte compartment having an insoluble anode and an anolyte therein. The catholyte compartment generally includes a substrate support member and a catholyte therein. In addition, the plating cell generally includes an ion-exchange membrane disposed between the anolyte compartment and the catholyte compartment and a pump in fluid communication with the anolyte compartment, the pump configured to provide an anolyte to the anolyte compartment having a linear velocity of between about 0.5 cm/sec to about 50 cm/sec. The method generally includes supplying an anolyte solution to an anolyte compartment disposed in a plating cell having an anolyte compartment and a catholyte compartment. The anolyte solution generally passes through the anolyte compartment at a linear velocity of between about 0.5 cm/sec to about 50 cm/sec. The method further includes plating a metal onto the substrate with a catholyte solution disposed in a catholyte compartment of the plating cell, the catholyte compartment and the anolyte compartment separated by an ion-exchange membrane, removing used anolyte solution from the plating cell and passing at least a portion of the used anolyte solution through a correction device including at least one of copper oxide, copper hydroxide and combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. provisional patentapplication No. ______ entitled Isoluble Anode Loop in CopperElectrodeposition Cell For Interconnect Formation, filed Aug. 6, 2002which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] Embodiments of the present invention generally relate to theremoval and reduction of oxygen in an electrochemical plating system.

[0004] 2. Description of the Related Art

[0005] Metallization for sub-quarter micron sized features is afoundational technology for present and future generations of integratedcircuit manufacturing processes. In devices such as ultra large scaleintegration-type devices, i.e., devices having integrated circuits withmore than a million logic gates, the multilevel interconnects that lieat the heart of these devices are generally formed by filling highaspect ratio interconnect features with a conductive material, such ascopper or aluminum. Conventionally, deposition techniques such aschemical vapor deposition (CVD) and physical vapor deposition (PVD) havebeen used to fill these interconnect features. However, as interconnectsizes decrease and aspect ratios increase, void-free interconnectfeature fill via conventional metallization techniques becomesincreasingly difficult. As a result thereof, plating techniques, such aselectrochemical plating (ECP) and electroless plating, for example, haveemerged as viable processes for filling sub-quarter micron sized highaspect ratio interconnect features in integrated circuit manufacturingprocesses.

[0006] In an ECP process sub-quarter micron sized high aspect ratiofeatures formed on a substrate surface may be efficiently filled with aconductive material, such as copper. ECP plating processes are generallytwo stage processes, wherein a seed layer is first formed over thesurface features of the substrate, and then the surface features of thesubstrate are exposed to an electrolyte solution while an electricalbias is simultaneously applied between the substrate and an anodepositioned within the electrolyte solution. The electrolyte solution isgenerally rich in ions to be plated onto the surface of the substrate.Therefore, the application of the electrical bias causes these ions tobe urged out of the electrolyte solution and to be plated as a metal onthe seed layer. The plated metal, which may be copper, for example,grows in thickness and forms a copper layer that fills the featuresformed on the substrate surface.

[0007] In order to facilitate and control this plating process, severaladditives may be utilized in the electrolyte plating solution. Forexample, a typical electrolyte solution used for copper electroplatingmay consist of copper sulfate solution, which provides the copper to beplated, having sulfuric acid and copper chloride added thereto. Thesulfuric acid may generally operate to modify the acidity andconductivity of the solution. The electrolytic solutions also generallycontain various organic molecules, which may be accelerators,suppressors, levelers, brighteners, etc. These organic molecules aregenerally added to the plating solution in order to facilitate void-freesuper-fill of high aspect ratio features and planarized copperdeposition.

[0008] Furthermore, conventional systems may utilize a soluble metalanode to provide a continuous supply to metal ions for electrolytereplenishment. However, anode dissolution has disadvantages such asundesirable side products, e.g., sludge and copper ball formation, andundesirable side effects, e.g., anode passiviation, non-uniform anodedissolution, and consumption/breakdown of organic additives. Therefore,an insoluble anode may be utilized in electrochemical plating systems.However, the electrical bias applied to the anode may cause oxygen toform, thereby saturating the plating solution with oxygen and oxygenbubbles. Oxygen bubbles may cause undesirable side-effects, such asnon-uniformity of the copper deposit distribution, formation of bubbleson the substrate, and blockage of the anode and membranes present in theplating cell. Therefore, there is a need for a method and apparatus thatminimize the formation and effects of oxygen in semiconductorelectroplating baths, wherein the method and apparatus addresses thedeficiencies of conventional devices.

SUMMARY OF THE INVENTION

[0009] Embodiments of the present invention generally relate to anelectrochemical plating system. The electrochemical plating systemgenerally includes a plating cell having an anolyte compartment and acatholyte compartment, the anolyte compartment having an insoluble anodeand an anolyte therein. The catholyte compartment generally includes asubstrate support member and a catholyte therein. In addition, theplating cell generally includes an ion-exchange membrane disposedbetween the anolyte compartment and the catholyte compartment and a pumpin fluid cocmunication with the anolyte compartment, the pump configuredto provide an anolyte to the anolyte compartment having a linearvelocity of between about 0.5 cm/sec to about 50 cm/sec.

[0010] Embodiments of the invention further include an electrochemicalplating system including a cation exchange membrane disposed between theanolyte compartment and the catholyte compartment, the cation exchangemembrane being selective to hydrogen ions and copper ions. Theelectrochemical plating system may further include a correction devicein fluid communication with the anolyte compartment, the correctiondevice including at least one of copper hydroxide, copper oxide, andcombinations thereof configured to neutralize excess acid in theanolyte.

[0011] Embodiments of the invention further include a method for platinga metal on a substrate. The method generally includes supplying ananolyte solution to an electrochemical plating cell having an anolytecompartment and a catholyte compartment. The anolyte solution generallypasses through the anolyte compartment at a linear velocity of betweenabout 0.5 cm/sec to about 50 cm/sec. The method further includes platinga metal onto the substrate with a catholyte solution disposed in thecatholyte compartment, the catholyte compartment and the anolytecompartment being separated by an ion-exchange membrane, removing usedanolyte solution from the plating cell and passing at least a portion ofthe used anolyte solution through a correction device including at leastone of copper oxide, copper hydroxide, and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of thepresent invention can be understood in detail, a more particulardescription of the invention, briefly summarized above, may be had byreference to embodiments, some of which are illustrated in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this invention and are thereforenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments.

[0013]FIG. 1 illustrates a plating system for use in embodiments of thepresent invention.

[0014]FIG. 2 illustrates a schematic view of an exemplary catholyte EDC.

[0015]FIG. 3 illustrates a plating system incorporating an anionicmembrane.

[0016]FIG. 4 illustrates an embodiment of an exemplary anolyte EDC.

[0017]FIG. 5 illustrates a perspective and partial sectional view of anexemplary electrochemical plating cell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018]FIG. 1 illustrates a plating system 100 for use in embodiments ofthe present invention. The plating system 100 generally includes aplating cell 101, which may be an electrochemical plating (ECP) cell forcopper superfill plating or another electroplating cell configurationknown in the semiconductor art. The ECP cell 101 is generally configuredto fluidly isolate an anode 122 of the plating cell 101 from a cathode124 or plating electrode of the plating cell 101 via a membrane 112positioned between the substrate 123 being plated and the anode 122 ofthe plating cell 101. Additionally, the plating cell 101 is generallyconfigured to provide a first plating solution (anolyte) to an anolytecompartment 108, i.e., the volume between the upper surface of the anode122 and the lower surface of the membrane 112, and a second fluidsolution (catholyte) to a catholyte compartment 110, i.e., the volume offluid positioned above the upper membrane surface. In addition, theplating cell 101 further includes an anolyte inlet 105 configured todeliver the anolyte to the plating cell 101 and an anolyte outlet ordrain 106 configured to remove anolyte from plating cell 101.

[0019] A rotating head 126 configured to expose a substrate depositionsurface to the plating solution generally supports the cathode electrode124. The anode 122 is generally insoluble and is not consumed in theplating process. The anode 122 may have a large surface area, therebyincreasing contact with the plating solution. For example, the anode 122may be a porous wire mesh, a sieve, or a metal grid formed of carbonfibers, carbon wool, sintered metal, or metallic titanium nitridefibers. The anode 122 may also be a thin disk or ring formed of titaniumor a solid platinum foil. The anode 122 may further include a coating ofplatinized platinum, platinum iridium, platinum alloys or other noblemetals stable in an acid medium under oxygen electroformation.

[0020] The membrane 112 is generally configured to prevent anodeby-products from entering the catholyte compartment 110, therebyincreasing plating performance by decreasing the amount of defectspresent on the plated substrate. In addition, the membrane 112 generallyprevents organic additive diffusion from the catholyte compartment 110to the anolyte compartment 108. Preventing additive migration to theanolyte compartment 108 prevents additive breakdown and contaminationgenerally caused by additive contact with the anode 122. The membrane112 may include an ion exchange membrane, such as a cation exchangemembrane or an anion exchange membrane.

[0021] These membranes may be one of many commercially availablemembranes. For example, Tokuyama Corporation manufactures and suppliesvarious hydrocarbon membranes for electrodialysis and relatedapplications under the trade name “Neosepta.” Perfluorinated cationmembranes, which are stable to oxidation and useful when it is necessaryto separate an insoluble anode compartment by a cation membrane, aregenerally available from DuPont Co as Nafion membranes N-117, N-450, orfrom Asahi Glass Company (Japan) under the trade name Flemion as Fx-50,F738, and F893 model membranes. Asahi Glass Company also produces a widerange of polystyrene based ion-exchange membranes under the trade nameSelemion, which can be very effective for concentration/desalination ofelectrolytes and organic removal (cation membranes CMV, CMD, and CMT andanion membranes AMV, AMT, and AMD). There are also companies thatmanufacture similar ion-exchange membranes (Solvay (France), SybronChemical Inc. (USA), lonics (USA), and FuMA-Tech (Germany) etc.).Further, in order to minimize the penetration of copper ions intocathode compartment, it may be helpful to separate this compartment by abipolar ion-exchange membrane that is made from cation and anionmembranes compiled together. Bipolar membranes, such as models AQ-BA-06and AQ-BA-04, for example, are commercially available from Aqualitics(USA) and Asahi Glass Co.

[0022] In operation, the membrane 112 generally does not contact theanode 122. Contact with the anode 122 generally affects platingperformance and anode 122 operation. Therefore, the membrane 112generally has a distance from the anode 122 of greater than about 0.1mm. Preferably, the membrane 112 has a distance from the anode 122 offrom about 0.5 mm to about 10 mm.

[0023] In certain embodiments, the plating cell 101 may further includea diffuser 128 disposed between a catholyte inlet 116 and the cathode124. The flow diffuser 128 provides a substantially uniform verticalvelocity of plating solution across the width of the plating cell 101above the flow diffuser 128. The uniformity of plating conditions acrossthe substrate 123 will therefore be enhanced due to the more uniformfluid flow conditions. The flow diffuser 128 is constructed to besubstantially rigid. In this disclosure, the term “rigid” indicatessufficient structural rigidity of the diffuser to limit sufficientdeformation or bending of the diffuser, under the normal operatingconditions in the process cell, which would alter the electricresistance between the anode and a seed layer deposited on the substratedeposition surface. Such deformation would bend the diffuser 128 so thecenter of the diffuser 128 is nearer the nearest location on thesubstrate 123 than the periphery of the diffuser 128 is to its closestlocation on the substrate 123. The flow diffuser 128 is preferablyformed from microscopic, generally spherical, ceramic particles that aresintered to the adjacent spherical ceramic particles of the flowdiffuser 128 at the points of spherical contact. Ceramic is a naturallyhydrophilic material. Other suitable, substantially rigid, materials mayalso be utilized. Voids or spaces are formed between the adjacentceramic particles. The diffuser 128 is designed with pores havingdimensions of from about 0.1 microns to about 500 microns. Since thefluid flow resistance through a flow diffuser 128 is a function of thedistance that the fluid travels through the flow diffuser 128, thevertical height of the diffuser 128 can be altered to provide desiredfluid flow characteristics. For example, a thicker flow diffuser 128with the same pore dimensions will provide an increased resistance tofluid flow through the flow diffuser 128 to provide a more restrictedfluid flow through the flow diffuser 128 having similar pore dimensions.Although a flow diffuser is described herein, any structure configuredto provide uniform flow known to one skilled in the art may be used.

[0024] The exemplary 100 plating system illustrated in FIG. 1 generallyincludes a cation exchange membrane 112. The cation exchange membrane112 generally is selective to positively charged ions, e.g., hydrogenions (H⁺) and copper ions (Cu²⁺); therefore the H⁺ and Cu²⁺ migrate fromthe anolyte compartment 108 to the catholyte compartment 110. Generally,the ions migrating from the anolyte compartment 108 to the catholytecompartment 110 should include from about 95% to about 98% Cu²⁺ ions.The Cu²⁺ migration is generally necessary to compensate for copperlosses in the catholyte solution due to copper plating. As a result ofcopper migration, the anolyte copper concentration decreases and becomesmore acidic over time.

[0025] When utilizing a cation exchange membrane 112, the anolytegenerally includes from about 0.05 M to about 1 M copper sulfate and aminimal amount of acid, e.g., an amount sufficient to provide an anolytepH of from about 2 to about 6, and more preferably to provide a pH offrom about 2.5 to about 4. The acid may include sulfuric acid,phosphoric acid, and/or derivatives thereof. In addition to, coppersulfate, the plating solution may include other copper salts, such ascopper fluoborate, copper gluconate, copper sulfamate, copper sulfonate,copper pyrophosphate, copper chloride, or copper cyanide, for example.However, embodiments of the invention are not limited to theseparameters. The anolyte may further include salts, such as metal ligandsor complexing agents, to prevent anode passivation or to reduce anodesludge formation.

[0026] The catholyte generally includes copper sulfate, sulfuric acid,and a small amount of copper chloride, e.g., from about 20 ppm to about80 ppm. The plating solution may further include one or more additives.Additives, which may be, for example, levelers, inhibitors, suppressors,brighteners, accelerators, or other additives known in the art,typically adsorb onto the surface of the substrate 123 being plated.Useful suppressors generally include polyethers, such as polyethyleneglycol, or other polymers, such as polyethylene-polypropylene oxides,which adsorb on the substrate surface, slowing down copper deposition inthe adsorbed areas. Useful accelerators generally include sulfides ordisulfides, such as bis(3-sulfopropyl) disulfide, which compete withsuppressors for adsorption sites, accelerating copper deposition inadsorbed areas. Useful levelers generally include thiadiazole,imidazole, and other nitrogen containing organics. Useful inhibitorstypically include sodium benzoate and sodium sulfite, which inhibit therate of copper deposition on the substrate 123. During plating, theadditives are consumed at the substrate surface, but are beingconstantly replenished by the plating solution. However, differences indiffusion rates of the various additives result in different surfaceconcentrations at the top and the bottom of features, thereby setting updifferent plating rates in features in the substrate 123. Ideally, theseplating rates should be higher at the bottom of the feature forbottom-up fill. Thus, an appropriate composition of additives in theplating solution is required to achieve a void-free fill of thefeatures.

[0027] The anolyte is delivered to the plating cell 101 via anolyteinlet 105, which is in fluid communication with an anolyte storage unit102. A fluid pump 104 is generally positioned between the anolytestorage unit 102 and the plating cell 101 and is configured to deliverthe anolyte to plating cell 101 at a high linear flow rate. Generally,the anolyte enters the anolyte compartment 108 at a flow rate sufficientto prevent oxygen saturation of the anolyte by minimizing the anolyteresidence time in the anolyte compartment 108. For example, the flowrate of the anolyte may be between about 0.5 L/min and about 20 L/min,and more particularly is between about 1 L/min and about 10 L/min. Theanolyte flow rate will generally depend upon the anolyte inlet 105diameter. For example, the larger the inlet, the lower the requiredanolyte flow rate.

[0028] In addition, the anolyte flow rate generally results in a desiredlinear velocity of from about 0.5 cm/sec to about 50 cm/sec. The linearvelocity at the anode 122 surface is a function of the anolyte flowrate, the anode diameter, and the distance between the anode 122 and themembrane 112. Therefore, the anolyte flow rate generally varies as afunction of the anode 122 cross-sectional area, i.e., the flow rate willbe different for a 200 cm substrate versus a 300 cm substrate. A highanolyte flow rate generally operates to reduce oxygen bubble formationat the anode 122 and excessive acidification of the anolyte as a resultof a shorter anolyte residence time near the anode 122, e.g., theanolyte is passing through the plating cell 101 faster than the timeneeded for oxygen saturation. Furthermore, any oxygen formed in theanolyte is removed from the anolyte compartment 108 by the high flow ofanolyte passing therethrough.

[0029] Although the high flow rate generally eliminates oxygenformation, systems utilizing lower anolyte flow rates may requireadditional treatment. Therefore, the anolyte outlet 106 may be generallyin fluid communication with an input of a column 130, that has an outputthereof, which is in fluid communication with a filter 134. Column 130may include more than one column, wherein one column contains copperoxide (CuO) and another column contains copper hydroxide (Cu(OH)₂). Whenutilizing more than one column, valves may control the flow of anolyteso that the anolyte may flow through either column depending on thedesired pH level of anolyte in the tank 102. FIG. 1 shows a singlecolumn, preferably including Cu(OH)₂, although any number of columns maybe used depending on system requirements. Generally, the system 100illustrated in FIG. 1 includes passing the anolyte to a valve 132disposed between the anolyte outlet 106 and the column 130. The flow ofanolyte to the column 130 may be split by the valve 132 and controlledby valves 132 and 140, with the remaining flow of anolyte passing to theanolyte storage tank 102. Determining the flow of anolyte through thecolumn 130 may include monitoring the pH of the anolyte in the anolytestorage tank 102. As the pH of the anolyte increases, with an anolyte pHof from about 2 to about 6 being preferable, a larger volume of anolytemay flow through the column 130.

[0030] The column 130 generally includes a housing having either CuO orCu(OH)₂, in powder or solid form, disposed therein. The powder may be ina cartridge, supported by a mesh support member, or supported by anothermeans known to one skilled in the art.

[0031] In operation, passing the anolyte through a column 130 containingcopper oxide or copper hydroxide results in the following reactions:

CuO+H₂SO₄═H₂O+CuSO₄  (1)

Cu(OH)₂+H₂SO₄═2H₂O+CuSO₄  (2)

[0032] The copper oxide or hydroxide dissolves upon contact with excessacid, thereby converting the excess acid present in the anolyte intocopper sulfate. Although described in terms of a column, the excess acidin the anolyte may be neutralized by any means known to one skilled inthe art. The anolyte may subsequently be passed through a filter 134configured to remove copper oxide and copper hydroxide remaining in theanolyte solution. For example, the anolyte may be passed through afilter 134. Upon treatment, the anolyte generally has a pH of from about2.6 to about 3.6. The filter 134 is generally in fluid communicationwith the anolyte storage unit 102. Furthermore, prior to passing theanolyte from the anolyte storage unit 102 to the plating cell 101, theanolyte may be passed through a removal device, such as a degasser 136.The degasser 136 is generally configured to remove at least of portionof dissolved gases, such as oxygen and nitrogen, from the anolyte priorto entry into the anolyte compartment 108.

[0033] Additionally, a catholyte outlet 114 may be in fluidcommunication with an input of an electrodialysis cell (EDC) 138, whichmay have an output thereof, which is in fluid communication with thecatholyte storage unit 118. The catholyte is recirculated to thecatholyte compartment via a catholyte inlet 116.

[0034] Generally, the EDC chamber 138 is configured to receive a portionof the used catholyte returning from plating cell 101 to catholytestorage unit 118. The received portion of used catholyte is neutralizedwithin the EDC 130 resulting in a restored catholyte, which may then bereintroduced into the catholyte storage unit 118 for subsequent use inplating operations. Although the exemplary EDC illustrated in FIG. 1receives the entire used catholyte passing through outlet 114, it iscontemplated that various configurations of EDCs may be implemented,which may receive only a portion of the used catholyte, e.g., via aslipstream type configuration.

[0035]FIG. 2 illustrates a schematic view of an exemplary catholyte EDC138. The exemplary EDC 138, for example, may be implemented into an ECPsystem configured to plate copper onto semiconductor substrates. Theexemplary EDC 138 generally includes an outer housing 200 configured tohold or confine the essential elements of EDC 138. A first end ofhousing 200 generally includes a copper anode source 202, while a secondend of housing 200 generally includes a cathode source 204. The anodesource 202 and cathode source 204 are generally positioned onopposite/opposing ends of the housing 200. The volume between thecathode source 204 and anode source 202 within the housing 200 generallyincludes a plurality of chambers, wherein the chambers generally includean anode chamber 206 and a cathode chamber 208 corresponding to theanode 202 or cathode 204 positioned in the respective end of housing200. Used catholyte is supplied to EDC cell 138 via conduit 210. Conduit210 supplies the used catholyte into an input chamber 212 in the EDCcell 138. Selectively permeable membranes individually separate therespective chambers.

[0036] An anion membrane 214, which is selective and penetrablepreferably to univalent anions, especially to SO4²⁻, generally separatesthe anode chamber 206 and the input chamber 212. A bipolar membrane 216separates the input chamber 212 and the cathode chamber 208. The cathodechamber 208 and anode chamber 206 may be supplied with a sulfuric acidsolution via conduits 218 and 220, which operate to circulate the acidsolution through the respective chamber. The sulfuric acid generally isdilute. Therefore, an additional conduit (not shown) may supplydeionized water to the respective chambers or to conduits 218 and 220.

[0037] In operation, an electrical bias is applied across EDC cell 128via anode 202 and cathode 204. Generally the voltage drop between thecathode 204 and anode 202 is from about 0.4 volts to about 1.5 volts.The application of the electrical bias across EDC cell 128 operates tourge ions in the used catholyte solution towards the respective poles,i.e., positive ions will be urged in the direction of the cathode 204,while negative ions will be urged in the direction of the anode 202.Therefore, the disassociated sulfate ions from the used catholyte, whichare generally illustrated as SO4²⁻ in FIG. 2, are urged in the directionof anode 202 out of the used catholyte solution. Similarly,disassociated hydroxide ions, which are generally illustrated as OH⁻,are urged in the direction of anode 202 and disassociated hydrogen ions,which are generally illustrated as H⁺ ions are urged in the direction ofthe cathode 204. Furthermore, although Cu²⁺ also penetrates the membrane216, the amount is negligible because the rate of H⁺ migrating to thecathode chamber 208 is about 100 times greater than the copper ionmigration. The hydroxide ions neutralize the excess acid present in thecatholyte. In addition, the bipolar membrane 216 allows for removal ofH⁺ ions from the used catholyte to further neutralize the excess acid.The formed acidic copper sulfate solution may then be removed from inputchamber 212 via conduit 222 and re-circulated into the plating system(or an electrolyte solution tank, etc.), as CuSO₄/H₂SO₄ are primaryelements of an electrolyte solution for a copper electroplating system.Therefore, EDC 138 generally operates to receive used electrolyte from aplating system and separate viable components (copper sulfate andsulfuric acid) from the used catholyte for reuse in the plating system.Although the excess acid is neutralized upon treatment, the copper inthe catholyte may remain depleted. Therefore, copper sulfate, along withadditives may be added to the catholyte storage tank 118. In addition,dry copper sulfate may be added to the catholyte either prior to dosingin the catholyte storage unit 118 or after storage. In addition,alternative embodiments of the EDC 138 may be implemented to furthercorrect the copper concentration. The alternative EDC may utilize acation membrane rather than an anion membrane and circulate aconcentrated copper sulfate solution through anode chamber 206 toprovide Cu²⁺ migration through the membrane and into the used catholyte.

[0038]FIG. 3 illustrates a plating system 300 incorporating an anionicmembrane 302. The plating system 300 varies from that shown in FIG. 1 inthat the anolyte generally is a diluted acid solution, e.g., from about0.05 M to about 0.1M. The acid generally is sulfuric acid. The anolytemay further include an organic or inorganic component reducer. Forexample, the anolyte may include dissolved gaseous hydrogen,hydroquinone, formic acid, Fe²⁺, Kl, or Mn²⁺, or combinations thereof.When gaseous hydrogen is included in the anolyte, the anolyte isgenerally saturated with hydrogen in the anolyte storage tank 102. Thecomponent reducer generally reduces on the anode 122 through thefollowing reaction, thereby limiting oxygen production:

H⁺═H₂+2e⁻  (3)

[0039] When utilizing an anionic membrane 302, the excess acid in theanolyte is generally neutralized. Therefore, the system 300 can includean EDC 304 in fluid communication with the anolyte outlet 106. FIG. 4illustrates an embodiment of an exemplary anolyte EDC 304. EDC 304 issimilarly constructed to EDC 138, in that ELDC 304 includes an anodechamber 400 and a cathode chamber 402. In similar fashion to ELDC 138,inlet 404 communicates used or aged anolyte from a plating cell, such asa copper ECP cell, into the input chambers 406 of ELDC 304. In thisconfiguration, a diluted, e.g., from about 0.01 M to about 0.1 M,sulfuric acid solution may pass through isolation chambers 408positioned in the anodic direction of the input chambers 404 via conduit410.

[0040] The membrane structure generally follows an alternating sequence,i.e., from left to right, an anionic membrane, then a cationic membrane,then an anionic membrane, then a cationic membrane, etc. In operation,ELDC 304 operates similarly to ELDC 138 illustrated in FIG. 2, as anelectrical bias is applied between cathode 204 and anode 202. Thereplenished anolyte may then be retrieved from the input chambers 404via conduit 412 for replenishment. The application of the electricalbias causes positively charged ions in the used anolyte solution tomigrate towards the cathode 204, while negatively charged ions are urgedto migrate towards the anode 202. The configuration of cationic andanionic membranes operates to urge positive hydrogen ions, negativehydroxide ions, and negatively charged sulfate ions between therespective membranes and into the desired chambers as illustrated inFIG. 4. The positive hydrogen ions and the negative sulfate ions combineto neutralize excess acid and form a diluted sulfuric acid solution,which may then be extracted from ELDC 304 for reuse in a copper platingsystem.

[0041]FIG. 5 illustrates a perspective and partial sectional view of anexemplary electrochemical plating cell 500 for use in the embodimentsdescribed above. Plating cell 500 generally includes an outer basin 501and an inner basin 502 positioned within outer basin 501. Inner basin502 is generally configured to contain a plating solution that is usedto plate a metal, e.g., copper, onto a substrate during anelectrochemical plating process. During the plating process, the platingsolution is generally continuously supplied to inner basin 502 (at about1 gallon per minute for a 10 liter plating cell, for example), andtherefore, the plating solution continually overflows the uppermostpoint of inner basin 502 and runs into outer basin 501. The overflowplating solution is then collected by outer basin 501 and drainedtherefrom for recirculation into basin 502. As illustrated in FIG. 5,plating cell 500 is generally positioned at a tilt angle, i.e., theframe portion 503 of plating cell 500 is generally elevated on one sidesuch that the components of plating cell 500 are tilted between about 3°and about 30°. Therefore, in order to contain an adequate depth ofplating solution within inner basin 502 during plating operations, theuppermost portion of basin 502 may be extended upward on one side ofplating cell 500, such that the uppermost point of inner basin 502 isgenerally horizontal and allows for contiguous overflow of the platingsolution supplied thereto around the perimeter of basin 502.

[0042] The frame member 503 of plating cell 500 generally includes anannular base member 504 secured to frame member 503. Since frame member503 is elevated on one side, the upper surface of base member 504 isgenerally tilted from the horizontal at an angle that corresponds to theangle of frame member 503 relative to a horizontal position. Base member504 includes an annular or disk shaped recess formed therein, theannular recess being configured to receive a disk shaped anode member505. Base member 504 further includes a plurality of fluid inlets/drains509 positioned on a lower surface thereof. Each of the fluidinlets/drains 509 are generally configured to individually supply ordrain a fluid to or from either the anode compartment or the cathodecompartment of plating cell 500. Plating cell 500 further includes amembrane support assembly 506. Membrane support assembly 506 isgenerally secured at an outer periphery thereof to base member 504, andincludes an interior region 508 configured to allow fluids to passtherethrough via a sequence of oppositely positioned slots and bores.The membrane support assembly may include an o-ring type seal positionednear a perimeter of the membrane, wherein the seal is configured toprevent fluids from traveling from one side of the membrane secured onthe membrane support 506 to the other side of the membrane.

[0043] In operation, the plating cell 500 of the invention provides asmall volume (electrolyte volume) processing cell that may be used forcopper electrochemical plating processes, for example. Plating cell 500may be horizontally positioned or positioned in a tilted orientation,i.e., where one side of the cell is elevated vertically higher than theopposing side of the cell, as illustrated in FIG. 5. If plating cell 505is implemented in a tilted configuration, then a tilted head assemblyand substrate support member may be utilized to immerse the substrate ata constant immersion angle, i.e., immerse the substrate such that theangle between the substrate and the upper surface of the electrolytedoes not change during the immersion process. Further, the immersionprocess may include a varying immersion velocity, i.e., an increasingvelocity as the substrate becomes immersed in the electrolyte solution.The combination of the constant immersion angle and the varyingimmersion velocity operates to eliminate air bubbles on the substratesurface.

[0044] Assuming a tilted implementation is utilized, a substrate isfirst immersed into a plating solution contained within inner basin 502.Once the substrate is immersed in the plating solution, which generallycontains copper sulfate, chlorine, and one or more of a plurality oforganic plating additives (levelers, suppressors, accelerators, etc.)configured to control plating parameters, an electrical plating bias isapplied between a seed layer on the substrate and the anode 505positioned in a lower portion of plating cell 500. The electricalplating bias generally operates to cause metal ions in the platingsolution to deposit on the cathodic substrate surface. The platingsolution supplied to inner basin 502 is continually circulated throughinner basin 502 via fluid inlet/outlets 509. More particularly, theplating solution may be introduced in plating cell 500 via a fluid inlet509. The solution may travel across the lower surface of base member 504and upward through one of fluid apertures 206. The plating solution maythen be introduced into the cathode chamber via a channel formed intoplating cell 500 that communicates with the cathode chamber at a pointabove membrane support 506. Similarly, the plating solution may beremoved from the cathode chamber via a fluid drain positioned abovemembrane support 506, where the fluid drain is in fluid communicationwith one of fluid drains 509 positioned on the lower surface of basemember 504. For example, base member 504 may include first and secondfluid apertures 206 positioned on opposite sides of base member 404. Theoppositely positioned fluid apertures 206 may operate to individuallyintroduce and drain the plating solution from the cathode chamber in apredetermined direction, which also allows for flow direction control.The flow control direction provides control over removal of light fluidsat the lower membrane surface, removal of bubbles from the anodechamber, and assists in the removal of dense or heavy fluids from theanode surface via the channels 202 formed into base 504.

[0045] Once the plating solution is introduced into the cathode chamber,the plating solution travels upward through diffusion plate 510.Diffusion plate 510, which is generally a ceramic or other porous diskshaped member, generally operates as a fluid flow restrictor to even outthe flow pattern across the surface of the substrate. Further, thediffusion plate 510 operates to resistively damp electrical variationsin the electrochemically active area the anode or cation membranesurface, which is known to reduce plating uniformities. Additionally,embodiments of the invention contemplate that the ceramic diffusionplate 510 may be replaced by a hydrophilic plastic member, i.e., atreated PE member, an PVDF member, a PP member, or other material thatis known to be porous and provide the electrically resistive dampingcharacteristics provided by ceramics. However, the plating solutionintroduced into the cathode chamber, which is generally a platingcatholyte solution, is not permitted to travel downward through themembrane (not shown) positioned on the lower surface 404 of membranesupport assembly 506 into the anode chamber, as the anode chamber isfluidly isolated from the cathode chamber by the membrane. The anodechamber includes separate individual fluid supply and drain sourcesconfigured to supply an anolyte solution to the anode chamber. Thesolution supplied to the anode chamber, which may generally be coppersulfate in a copper electrochemical plating system, circulatesexclusively through the anode chamber and does not diffuse or otherwisetravel into the cathode chamber, as the membrane positioned on membranesupport assembly 506 is not fluid permeable in either direction.

[0046] Additionally, the flow of the fluid solution (anolyte) into theanode chamber is directionally controlled in order to maximize platingparameters. For example, anolyte may be communicated to the anodechamber via an individual fluid inlet 509. Fluid inlet 509 is in fluidcommunication with a fluid channel formed into a lower portion of basemember 504 and the fluid channel communicates the anolyte to one ofapertures 205. Thereafter, the anolyte generally travels across theupper surface of the anode 505 towards the opposing side of base member504, which in a tilted configuration, is generally the higher side ofplating cell 500. The anolyte travels across the surface of the anodebelow the membrane positioned immediately above. Once the anolytereaches the opposing side of anode 505, it is received into acorresponding fluid channel 204 and drained from plating cell 504 forrecirculation thereafter.

[0047] During plating operations, the application of the electricalplating bias between the anode and the cathode generally causes achemical reaction on the anode, resulting in oxygen bubbles in theanolyte. However, the high anolyte flow rate operates to minimize theanolyte residence time at the anode, thereby preventing oxygensaturation. Furthermore, the removal device and the columns operate toremove any formed oxygen in the anolyte.

[0048] While the foregoing is directed to embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An electrochemical plating system, comprising: aplating cell having an anolyte compartment and a catholyte compartment,the anolyte compartment having an insoluble anode and an anolytesolution therein, the catholyte compartment having a cathode substratesupport member and a catholyte solution therein; an ion-exchangemembrane disposed between the anolyte compartment and the catholytecompartment; and a pump in fluid communication with the anolyte inletpositioned in fluid communication with the anolyte compartment, the pumpbeing configured to provide an anolyte solution to the anolytecompartment at a linear velocity sufficient to prevent saturation of theanolyte with oxygen.
 2. The electrochemical plating system of claim 1,wherein the linear velocity is between about 0.5 cm/sec and about 50cm/sec.
 3. The electrochemical plating system of claim 1, furthercomprising an anolyte storage unit in fluid communication with theanolyte compartment.
 4. The electrochemical plating system of claim 1,further comprising a catholyte storage unit in fluid communication withthe catholyte compartment.
 5. The electrochemical plating system ofclaim 1, wherein the anode comprises at least one of titanium, platinum,noble metals, and combinations thereof.
 6. The electrochemical platingsystem of claim 1, wherein the ion-exchange membrane is positionedgreater than about 0.1 cm above the insoluble anode.
 7. Theelectrochemical plating system of claim 1, wherein the ion-exchangemembrane is positioned between about 0.5 cm and about 10 cm above theinsoluble anode.
 8. The electrochemical plating system of claim 1,further comprising a ceramic diffuser disposed between the ion-exchangemembrane and the cathode substrate support member.
 9. Theelectrochemical plating system of claim 1, wherein the ion-exchangemembrane comprises a cation membrane selective to hydrogen ions andcopper ions.
 10. The electrochemical plating system of claim 1, furthercomprising a correction device in fluid communication with the anolytecompartment, the correction device comprising at least one of copperhydroxide, copper oxide, and combinations thereof configured toneutralize excess acid in the anolyte.
 11. The electrochemical platingsystem of claim 10, further comprising a selectively actuated valvedisposed between an anolyte outlet and the correction device, the valveconfigured to adjust the flow of anolyte to the correction device. 12.The electrochemical plating system of claim 11, wherein the selectivelyactuated valve is configured to adjust the flow of anolyte to thecorrection device when the pH of the anolyte in an anolyte storage tankexceeds about
 6. 13. The electrochemical plating system of claim 10,further comprising a filter in fluid communication with the correctiondevice, the filter configured to remove excess copper hydroxide orcopper oxide from the anolyte and form corrected anolyte.
 14. Theelectrochemical plating system of claim 13, wherein the correctedanolyte has a pH of from about 2.6 to about 3.6.
 15. The electrochemicalplating system of claim 8, wherein the anolyte comprises copper sulfatein a concentration of from about 0.05 M to about 1.0 M and has a pH offrom about 2 to about
 6. 16. The electrochemical plating system of claim8, wherein the anolyte comprises copper sulfate in a concentration offrom about 0.05 M to about 1.0 M and has a pH of from about 2.5 to about4.
 17. The electrochemical plating system of claim 8, wherein thecatholyte comprises copper sulfate, sulfuric acid, organic additives,and copper chloride in an amount of from about 20 ppm to about 80 ppm.18. The electrochemical plating system of claim 1, further comprising acatholyte electrodialysis cell in fluid communication with the catholytecompartment, the catholyte electrodialysis cell being configured tocorrect a used catholyte concentration.
 19. The electrochemical platingsystem of claim 18, wherein the catholyte electrodialysis devicecomprises: a housing having a cathode electrode and an anode electrode;an anode chamber positioned proximate the anode electrode and betweenthe cathode electrode and the anode electrode, wherein the anode chamberis configured to receive a sulfuric acid solution; a cathode chamberpositioned proximate the cathode electrode and between the cathodeelectrode and the anode chamber, wherein the cathode chamber isconfigured to receive a sulfuric acid solution; an input chamberpositioned between the cathode chamber and the anode chamber, whereinthe input chamber is configured to receive the used catholyte solution;an anion membrane positioned between the anode chamber and the inputchamber configured to remove sulfate ions from the used catholytesolution; and a bipolar membrane positioned between the cathode chamberand the input chamber configured to remove hydrogen ions from the usedcatholyte solution and provide hydroxide ions to the used catholytesolution.
 20. The electrochemical plating system of claim 1, furthercomprising a removal device in fluid communication with the anolytecompartment, the removal device configured to remove at least a portionof dissolved gases from the anolyte.
 21. The electrochemical platingsystem of claim 20, wherein the dissolved gases comprise oxygen.
 22. Theelectrochemical plating system of claim 1, wherein the ion-exchangemembrane comprises an anion membrane selective to sulfate ions.
 23. Theelectrochemical plating system of claim 22, further comprising ananolyte electrodialysis cell in fluid communication with the anolytecompartment, the anolyte electrodialysis cell being configured tocorrect a used anolyte concentration.
 24. The electrochemical platingsystem of claim 23, wherein the anolyte electrodialysis devicecomprises: a housing having a cathode electrode and an anode electrode;an anode chamber positioned proximate the anode electrode and betweenthe cathode electrode and the anode electrode, wherein the anode chamberis configured to receive the used anolyte solution; a cathode chamberpositioned proximate the cathode electrode and between the cathodeelectrode and the anode chamber, wherein the cathode chamber isconfigured to receive the used anolyte solution; at least one inputchamber positioned between the cathode chamber and the anode chamber,wherein the input chamber is configured to receive the used anolytesolution; at least one isolation chamber positioned in the anodicdirection of the at least one input chamber configured to receive asulfuric acid solution; an anion membrane positioned in the anodicdirection of the input chamber configured to remove sulfate ions fromthe used catholyte solution; and a cation membrane positioned in thecathodic direction of the at least one input chamber configured toremove hydrogen ions from the used catholyte solution.
 25. Theelectrochemical plating system of claim 22, wherein the anolytecomprises sulfuric acid.
 26. An electrochemical plating system,comprising: a plating cell having an anolyte compartment and a catholytecompartment, the anolyte compartment having an insoluble anode and ananolyte solution therein, the catholyte compartment having a cathodesubstrate support member and a catholyte solution therein; a cationexchange membrane disposed between the anolyte compartment and thecatholyte compartment, the cation exchange membrane being selective tohydrogen ions and copper ions; and a correction device in fluidcommunication with the anolyte compartment, the correction devicecomprising at least one of copper hydroxide, copper oxide, andcombinations thereof configured to neutralize excess acid in theanolyte.
 27. The electrochemical plating system of claim 25, furthercomprising a pump in fluid communication with an anolyte inletpositioned in fluid communication with the anolyte compartment, the pumpbeing configured to provide an anolyte to the anolyte chamber having alinear velocity of between about 0.5 cm/sec to about 50 cm/sec.
 28. Theelectrochemical plating system of claim 27, wherein the pump isconfigured to provide an anolyte having a flow rate of from less thanabout 6 L/min.
 29. The electrochemical plating system of claim 25,further comprising a selectively actuated valve disposed between ananolyte outlet and the correction device, the valve configured to adjustthe flow of anolyte to the correction device.
 30. The electrochemicalplating system of claim 25, wherein the selectively actuated valve isconfigured to adjust the flow of anolyte to the correction device whenthe pH of the anolyte in an anolyte storage tank exceeds about
 6. 31. Amethod for plating a metal onto a substrate, comprising: supplying ananolyte solution to a plating cell having an anolyte compartment and acatholyte compartment, the anolyte solution passing through the anolytecompartment at linear velocity of between about 0.5 cm/sec and about 50cm/sec; plating a metal onto a substrate in the plating cell with acatholyte solution disposed in the catholyte compartment, the catholytecompartment and the anolyte compartment separated by an ion-exchangemembrane; removing used anolyte solution from the plating cell; andpassing at least a portion of the used anolyte solution through acorrection device comprising at least one of copper oxide, copperhydroxide, and combinations thereof.
 32. The method of claim 31, furthercomprising the passing the used anolyte solution through a removaldevice configured to remove at least a portion of dissolved gases fromthe anolyte.
 33. The method of claim 32, wherein the dissolved gasescomprise oxygen.
 34. The method of claim 31, further comprisingmonitoring a pH level of the anolyte contained in an anolyte storagetank, the anolyte storage tank being in fluid communication with thecorrection device.
 35. The method of claim 34, further comprisingincreasing the flow of anolyte passing through the removal device whenthe pH of the anolyte contained in the anolyte storage tank is greaterthan about
 6. 36. The method of claim 31, further comprising saturatingthe anolyte solution with hydrogen prior to passing the anolyte solutionthrough the anolyte compartment.
 37. The method of claim 31, furthercomprising an insoluble anode disposed in the anolyte compartment. 38.The method of claim 31, wherein the metal comprises copper.